TGF-β1-mediated differentiation of fibroblasts is associated with increased mitochondrial content and cellular respiration

Label-free three-dimensional imaging and quantitative analysis of living fibroblasts and myofibroblasts by holotomographic microscopy

Holotomography (HT) is a cutting-edge fast live-cell quantitative label-free imaging technique. Based on the principle of quantitative phase imaging, it combines holography and tomography to record a three-dimensional map of the refractive index, used as intrinsic optical and quantitative imaging contrast parameter of biological samples, at a sub-micrometer spatial resolution. In this study HT has been employed for the first time to analyze the changes of fibroblasts differentiating towards myofibroblasts - recognized as the main cell player of fibrosis - when cultured in vitro with the pro-fibrotic factor, namely transforming growth factor-β1. In parallel, F-actin, vinculin, α-smooth muscle actin, phospho-myosin light chain 2, type-1 collagen, peroxisome proliferator-activated receptor-gamma coactivator-1α expression and mitochondria were evaluated by confocal laser scanning microscopy. Plasmamembrane passive properties and transient receptor potential canonical channels' currents were also recorded by whole-cell patch-clamp. The fluorescence images and electrophysiological results have been compared to the data obtained by HT and their congruence has been discussed. HT turned out to be a valid approach to morphologically distinguish fibroblasts from well differentiated myofibroblasts while obtaining objective measures concerning volume, surface area, projection area, surface index and dry mass (i.e., the mass of the non-aqueous content inside the cell including proteins and subcellular organelles) of the entire cell, nuclei and nucleoli with the major advantage to monitor outer and inner features in living cells in a non-invasive, rapid and label-free approach. HT might open up new research opportunities in the field of fibrotic diseases. RESEARCH HIGHLIGHTS: Holotomography (HT) is a label-free laser interferometric imaging technology exploiting the intrinsic optical property of cells namely refractive index (RI) to enable a direct imaging and analysis of whole cells or intracellular organelles. HT turned out a valid approach to distinguish morphological features of living unlabeled fibroblasts from differentiated myofibroblasts. HT provided quantitative information concerning volume, surface area, projection area, surface index and dry mass of the entire fibroblasts/myofibroblasts, nuclei and nucleoli.

Significance of quantitative analyses of the impact of heterogeneity in mitochondrial content and shape on cell differentiation

Mitochondria, classically known as the powerhouse of cells, are unique double membrane-bound multifaceted organelles carrying a genome. Mitochondrial content varies between cell types and precisely doubles within cells during each proliferating cycle. Mitochondrial content also increases to a variable degree during cell differentiation triggered after exit from the proliferating cycle. The mitochondrial content is primarily maintained by the regulation of mitochondrial biogenesis, while damaged mitochondria are eliminated from the cells by mitophagy. In any cell with a given mitochondrial content, the steady-state mitochondrial number and shape are determined by a balance between mitochondrial fission and fusion processes. The increase in mitochondrial content and alteration in mitochondrial fission and fusion are causatively linked with the process of differentiation. Here, we critically review the quantitative aspects in the detection methods of mitochondrial content and shape. Thereafter, we quantitatively link these mitochondrial properties in differentiating cells and highlight the implications of such quantitative link on stem cell functionality. Finally, we discuss an example of cell size regulation predicted from quantitative analysis of mitochondrial shape and content. To highlight the significance of quantitative analyses of these mitochondrial properties, we propose three independent rationale based hypotheses and the relevant experimental designs to test them.

Inflammatory Markers Involved in the Pathogenesis of Dupuytren's Contracture

Dupuytren's disease is a common fibroproliferative disease that can result in debilitating hand deformities. Partial correction and return of deformity are common with surgical or clinical treatments at present. While current treatments are limited to local procedures for relatively late effects of the disease, the pathophysiology of this connective tissue disorder is associated with both local and systemic processes (e.g., fibrosis, inflammation). Hence, a better understanding of the systemic circulation of Dupuytren related cytokines and growth factors may provide important insights into disease progression. In addition, systemic biomarker analysis could yield new concepts for treatments of Dupuytren that attenuate circulatory factors (e.g., anti-inflammatory agents, neutralizing antibodies). Progress in the development of any disease modifying biologic treatment for Dupuytren has been hampered by the lack of clinically useful biomarkers. The characterization of nonsurgical Dupuytren biomarkers will permit disease staging from diagnostic and prognostic perspectives, as well as allows evaluation of biologic responses to treatment. Identification of such markers may transcend their use in Dupuytren treatment, because fibrotic biological processes fundamental to Dupuytren are relevant to fibrosis in many other connective tissues and organs with collagen-based tissue compartments. There is a wide range of potential Dupuytren biomarker categories that could be informative, including disease determinants linked to genetics, collagen metabolism, as well as immunity and inflammation (e.g., cytokines, chemokines). This narrative review provides a broad overview of previous studies and emphasizes the importance of inflammatory mediators as candidate circulating biomarkers for monitoring Dupuytren's disease.

Metabolic mechanisms in physiological and pathological cardiac hypertrophy: new paradigms and challenges

Cardiac metabolism is vital for heart function. Given that cardiac contraction requires a continuous supply of ATP in large quantities, the role of fuel metabolism in the heart has been mostly considered from the perspective of energy production. However, the consequence of metabolic remodelling in the failing heart is not limited to a compromised energy supply. The rewired metabolic network generates metabolites that can directly regulate signalling cascades, protein function, gene transcription and epigenetic modifications, thereby affecting the overall stress response of the heart. In addition, metabolic changes in both cardiomyocytes and non-cardiomyocytes contribute to the development of cardiac pathologies. In this Review, we first summarize how energy metabolism is altered in cardiac hypertrophy and heart failure of different aetiologies, followed by a discussion of emerging concepts in cardiac metabolic remodelling, that is, the non-energy-generating function of metabolism. We highlight challenges and open questions in these areas and finish with a brief perspective on how mechanistic research can be translated into therapies for heart failure.

Cardiac Fibrosis in heart failure: Focus on non-invasive diagnosis and emerging therapeutic strategies

Heart failure is a leading cause of mortality and hospitalization worldwide. Cardiac fibrosis, resulting from the excessive deposition of collagen fibers, is a common feature across the spectrum of conditions converging in heart failure. Eventually, either reparative or reactive in nature, in the long-term cardiac fibrosis contributes to heart failure development and progression and is associated with poor clinical outcomes. Despite this, specific cardiac antifibrotic therapies are lacking, making cardiac fibrosis an urgent unmet medical need. In this context, a better patient phenotyping is needed to characterize the heterogenous features of cardiac fibrosis to advance toward its personalized management. In this review, we will describe the different phenotypes associated with cardiac fibrosis in heart failure and we will focus on the potential usefulness of imaging techniques and circulating biomarkers for the non-invasive characterization and phenotyping of this condition and for tracking its clinical impact. We will also recapitulate the cardiac antifibrotic effects of existing heart failure and non-heart failure drugs and we will discuss potential strategies under preclinical development targeting the activation of cardiac fibroblasts at different levels, as well as targeting additional extracardiac processes.

Role of alpha smooth muscle actin in odontogenic differentiation of dental pulp stem cells

Pulpotomy is an effective treatment for retaining vital pulp after pulp exposure caused by caries removal and/or trauma. The expression of alpha smooth muscle actin (α-SMA) is increased during the wound-healing process, and α-SMA-positive fibroblasts accelerate tissue repair. However, it remains largely unknown whether α-SMA-positive fibroblasts influence pulpal repair. In this study, we established an experimental rat pulpotomy model and found that the expression of α-SMA was increased in dental pulp after pulpotomy relative to that in normal dental pulp. In vitro results showed that the expression of α-SMA was increased during the induction of odontogenic differentiation in dental pulp stem cells (DPSCs) compared with untreated DPSCs. Moreover, α-SMA overexpression promoted the odontogenic differentiation of DPSCs via increasing mitochondrial function. Mechanistically, α-SMA overexpression activated the mammalian target of rapamycin (mTOR) signaling pathway. Inhibition of the mTOR signaling pathway by rapamycin decreased the mitochondrial function in α-SMA-overexpressing DPSCs and suppressed the odontogenic differentiation of DPSCs. Furthermore, we found that α-SMA overexpression increased the secretion of transforming growth factor beta-1 (TGF-β1). In sum, our present study demonstrates a novel mechanism by which α-SMA promotes odontogenic differentiation of DPSCs by increasing mitochondrial respiratory activity via the mTOR signaling pathway.

Generation and characterization of two immortalized dermal fibroblast cell lines from the spiny mouse (Acomys)

The spiny mouse (Acomys) is gaining popularity as a research organism due to its phenomenal regenerative capabilities. Acomys recovers from injuries to several organs without fibrosis. For example, Acomys heals full thickness skin injuries with rapid re-epithelialization of the wound and regeneration of hair follicles, sebaceous glands, erector pili muscles, adipocytes, and dermis without scarring. Understanding mechanisms of Acomys regeneration may uncover potential therapeutics for wound healing in humans. However, access to Acomys colonies is limited and primary fibroblasts can only be maintained in culture for a limited time. To address these obstacles, we generated immortalized Acomys dermal fibroblast cell lines using two methods: transfection with the SV40 large T antigen and spontaneous immortalization. The two cell lines (AcoSV40 and AcoSI-1) maintained the morphological and functional characteristics of primary Acomys fibroblasts, including maintenance of key fibroblast markers and ECM deposition. The availability of these cells will lower the barrier to working with Acomys as a model research organism, increasing the pace at which new discoveries to promote regeneration in humans can be made.

Anti-fibrotic effects of statin drugs: a review of evidence and mechanisms

Fibrosis is a pathological repair process common among organs, that responds to damage by replacement of tissue with non-functional connective tissue. Despite the widespread prevalence of tissue fibrosis, manifesting in numerous disease states across myriad organs, therapeutic modalities to prevent or alleviate fibrosis are severely lacking in quantity and efficacy. Alongside development of new drugs, repurposing of existing drugs may be a complementary strategy to elect anti-fibrotic compounds for pharmacologic treatment of tissue fibrosis. Drug repurposing can provide key advantages to de novo drug discovery, harnessing the benefits of previously elucidated mechanisms of action and already existing pharmacokinetic profiles. One class of drugs a wealth of clinical data and extensively studied safety profiles is the statins, a class of antilipidemic drugs widely prescribed for hypercholesterolemia. In addition to these widely utilized lipid-lowering effects, increasing data from cellular, pre-clinical mammalian, and clinical human studies have also demonstrated that statins are able to alleviate tissue fibrosis originating from a variety of pathological insults via lesser-studied, pleiotropic effects of these drugs. Here we review literature demonstrating evidence for direct effects of statins antagonistic to fibrosis, as well as much of the available mechanistic data underlying these effects. A more complete understanding of the anti-fibrotic effects of statins may enable a clearer picture of their anti-fibrotic potential for various clinical indications. Additionally, more lucid comprehension of the mechanisms by which statins exert anti-fibrotic effects may aid in development of novel therapeutic agents that target similar pathways but with greater specificity or efficacy.

Mitochondrial quality control in cardiac fibrosis: Epigenetic mechanisms and therapeutic strategies

Cardiac fibrosis (CF) is considered an ultimate common pathway of a wide variety of heart diseases in response to diverse pathological and pathophysiological stimuli. Mitochondria are characterized as isolated organelles with a double-membrane structure, and they primarily contribute to and maintain highly dynamic energy and metabolic networks whose distribution and structure exert potent support for cellular properties and performance. Because the myocardium is a highly oxidative tissue with high energy demands to continuously pump blood, mitochondria are the most abundant organelles within mature cardiomyocytes, accounting for up to one-third of the total cell volume, and play an essential role in maintaining optimal performance of the heart. Mitochondrial quality control (MQC), including mitochondrial fusion, fission, mitophagy, mitochondrial biogenesis, and mitochondrial metabolism and biosynthesis, is crucial machinery that modulates cardiac cells and heart function by maintaining and regulating the morphological structure, function and lifespan of mitochondria. Certain investigations have focused on mitochondrial dynamics, including manipulating and maintaining the dynamic balance of energy demand and nutrient supply, and the resultant findings suggest that changes in mitochondrial morphology and function may contribute to bioenergetic adaptation during cardiac fibrosis and pathological remodeling. In this review, we discuss the function of epigenetic regulation and molecular mechanisms of MQC in the pathogenesis of CF and provide evidence for targeting MQC for CF. Finally, we discuss how these findings can be applied to improve the treatment and prevention of CF.

Mitochondrial folate pathway regulates myofibroblast differentiation and silica-induced pulmonary fibrosis

BACKGROUND

Silica-induced pulmonary fibrosis (silicosis) is a diffuse interstitial fibrotic disease characterized by the massive deposition of extracellular matrix in lung tissue. Fibroblast to myofibroblast differentiation is crucial for the disease progression. Inhibiting myofibroblast differentiation may be an effective way for pulmonary fibrosis treatment.

METHODS

The experiments were conducted in TGF-β treated human lung fibroblasts to induce myofibroblast differentiation in vitro and silica treated mice to induce pulmonary fibrosis in vivo.

RESULTS

By quantitative mass spectrometry, we revealed that proteins involved in mitochondrial folate metabolism were specifically upregulated during myofibroblast differentiation following TGF-β stimulation. The expression level of proteins in mitochondrial folate pathway, MTHFD2 and SLC25A32, negatively regulated myofibroblast differentiation. Moreover, plasma folate concentration was significantly reduced in patients and mice with silicosis. Folate supplementation elevated the expression of MTHFD2 and SLC25A32, alleviated oxidative stress and effectively suppressed myofibroblast differentiation and silica-induced pulmonary fibrosis in mice.

CONCLUSION

Our study suggests that mitochondrial folate pathway regulates myofibroblast differentiation and could serve as a potential target for ameliorating silica-induced pulmonary fibrosis.

Glycolytic reprogramming is involved in tissue remodeling on chronic rhinosinusitis

BACKGROUND

Glycolytic reprogramming is a key feature of chronic inflammatory disease. Extracellular matrix (ECM) produced by myofibroblasts plays an important role in tissue remodeling of nasal mucosa in chronic rhinosinusitis (CRS). This study aimed to determine whether glycolytic reprogramming contributes to myofibroblast differentiation and ECM production in nasal fibroblasts.

METHODS

Primary nasal fibroblasts were isolated from the nasal mucosa of patients with CRS. Glycolytic reprogramming was assessed by measuring the extracellular acidification and oxygen consumption rates in nasal fibroblast, with and without transforming growth factor beta 1 (TGF-β1) treatment. Expression of glycolytic enzymes and ECM components was measured by real-time polymerase chain reaction, western blotting, and immunocytochemical staining. Gene set enrichment analysis was performed using whole RNA-sequencing data of nasal mucosa of healthy donors and patients with CRS.

RESULT

Glycolysis of nasal fibroblasts stimulated with TGF-B1 was upregulated along with glycolytic enzymes. Hypoxia-inducing factor (HIF)-1α was a high-level regulator of glycolysis, and increased HIF-1α expression promoted glycolysis of nasal fibroblasts, and inhibition of HIF-1α down-regulated myofibroblasts differentiation and ECM production.

CONCLUSION

This study suggests that inhibition of the glycolytic enzyme and HIF-1α in nasal fibroblasts regulates myofibroblast differentiation and ECM generation associated with nasal mucosa remodeling.

NADPH oxidase 4 is dispensable for skin myofibroblast differentiation and wound healing

Differentiation of fibroblasts to myofibroblasts is governed by the transforming growth factor beta (TGF-β) through a mechanism involving redox signaling and generation of reactive oxygen species (ROS). Myofibroblasts synthesize proteins of the extracellular matrix (ECM) and display a contractile phenotype. Myofibroblasts are predominant contributors of wound healing and several pathological states, including fibrotic diseases and cancer. Inhibition of the ROS-generating enzyme NADPH oxidase 4 (NOX4) has been proposed to mitigate fibroblast to myofibroblast differentiation and to offer a therapeutic option for the treatment of fibrotic diseases. In this study, we addressed the role of NOX4 in physiological wound healing and in TGF-β-induced myofibroblast differentiation. We explored the phenotypic changes induced by TGF-β in primary skin fibroblasts isolated from Nox4-deficient mice by immunofluorescence, Western blotting and RNA sequencing. Mice deficient for Cyba, the gene coding for p22^phox, a key subunit of NOX4 were used for confirmatory experiments as well as human primary skin fibroblasts. In vivo, the wound healing was similar in wild-type and Nox4-deficient mice. In vitro, despite a strong upregulation following TGF-β treatment, Nox4 did not influence skin myofibroblast differentiation although a putative NOX4 inhibitor GKT137831 and a flavoprotein inhibitor diphenylene iodonium mitigated this mechanism. Transcriptomic analysis revealed upregulation of the mitochondrial protein Ucp2 and the stress-response protein Hddc3 in Nox4-deficient fibroblasts, which had however no impact on fibroblast bioenergetics. Altogether, we provide extensive evidence that NOX4 is dispensable for wound healing and skin fibroblast to myofibroblast differentiation, and suggest that another H₂O₂-generating flavoprotein drives this mechanism.

Protein conformation stabilized by newly formed turns for thermal resilience

Thermally stable or resilient proteins are usually stabilized at intermediate states during thermal stress to prevent irreversible denaturation. However, the mechanism by which their conformations are stabilized to resist high temperature remains elusive. Herein, we investigate the conformational and thermal stability of transforming growth factor-β1 (TGF-β1), a key signaling molecule in numerous biological pathways. We report that the TGF-β1 molecule is thermally resilient as it gradually denatures during thermal treatment when the temperature increases to 90°C-100°C but recovers native folding when the temperature decreases. Using this protein as a model, further studies show the maintenance of its bioactive functional properties after thermal stress, as demonstrated by differentiation induction of NIH/3T3 fibroblasts and human mesenchymal stem cells into myofibroblasts and chondrocytes, respectively. Molecular dynamic simulations revealed that although the protein's secondary structure is unstable under thermal stress, its conformation is partially stabilized by newly formed turns. Given the importance and/or prevalence of TGF-β1 in biological processes, potential therapeutics, and the human diet, our findings encourage consideration of its thermostability for biomedical applications and nutrition.

"Gingival Soft Tissue Integrative" Lithium Disilicate Glass-Ceramics with High Mechanical Properties and Sustained-Release Lithium Ions

Due to their good mechanical performances and high biocompatibility, all-ceramic materials are widely applied in clinics, especially in orthopedic and dental areas. However, the "hard" property negatively affects its integration with "soft" tissue, which greatly limits its application in soft tissue-related areas. For example, dental implant all-ceramic abutments should be well integrated with the surrounding gingival soft tissue to prevent the invasion of bacteria. Mimicking the gingival soft tissue and dentine integration progress, we applied the modified ion-exchange technology to "activate" the biological capacity of lithium disilicate glass-ceramics, via introducing OH^- to weaken the stability of Si-O bonds and release lithium ions to promote multi-reparative functions of gingival fibroblasts. The underlying mechanism was found to be closely related to the activation of mitochondrial activity and oxidative phosphorylation. In addition, during the ion-exchange process, the larger radius sodium ions (Na⁺) replaced the smaller radius lithium ions (Li⁺), so that the residual compressive stress was applied to the glass-ceramics surface to counteract the tensile stress, thus improving the mechanical properties. This successful case in simultaneous improvement of mechanical properties and biological activities proves the feasibility of developing "soft tissue integrative" all-ceramic materials with high mechanical properties. It proposes a new strategy to develop advanced bioactive and high strength all-ceramic materials by modified ion-exchange, which can pave the way for the extended applications of such all-ceramic materials in soft tissue-related areas.

Cardiac fibroblasts and mechanosensation in heart development, health and disease

The term 'mechanosensation' describes the capacity of cells to translate mechanical stimuli into the coordinated regulation of intracellular signals, cellular function, gene expression and epigenetic programming. This capacity is related not only to the sensitivity of the cells to tissue motion, but also to the decryption of tissue geometric arrangement and mechanical properties. The cardiac stroma, composed of fibroblasts, has been historically considered a mechanically passive component of the heart. However, the latest research suggests that the mechanical functions of these cells are an active and necessary component of the developmental biology programme of the heart that is involved in myocardial growth and homeostasis, and a crucial determinant of cardiac repair and disease. In this Review, we discuss the general concept of cell mechanosensation and force generation as potent regulators in heart development and pathology, and describe the integration of mechanical and biohumoral pathways predisposing the heart to fibrosis and failure. Next, we address the use of 3D culture systems to integrate tissue mechanics to mimic cardiac remodelling. Finally, we highlight the potential of mechanotherapeutic strategies, including pharmacological treatment and device-mediated left ventricular unloading, to reverse remodelling in the failing heart.

Exploring metabolism in scleroderma reveals opportunities for pharmacological intervention for therapy in fibrosis

Background

Recent evidence has indicated that alterations in energy metabolism play a critical role in the pathogenesis of fibrotic diseases. Studies have suggested that ‘metabolic reprogramming’ involving the glycolysis and oxidative phosphorylation (OXPHOS) in cells lead to an enhanced generation of energy and biosynthesis. The aim of this study was to assess the molecular basis of changes in fibrotic metabolism in systemic sclerosis (Scleroderma; SSc) and highlight the most appropriate targets for anti-fibrotic therapies.

Materials and methods

Dermal fibroblasts were isolated from five SSc patients and five healthy donors. Cells were cultured in medium with/without TGF-β1 and with/without ALK5, pan-PIM or ATM kinase inhibitors. Extracellular flux analyses were performed to evaluate glycolytic and mitochondrial respiratory function. The mitochondrial network in TMRM-stained cells was visualized by confocal laser-scanning microscopy, followed by semi-automatic analysis on the ImageJ platform. Protein expression of ECM and fibroblast components, glycolytic enzymes, subunits of the five OXPHOS complexes, and dynamin-related GTPases and receptors involved in mitochondrial fission/fusion were assessed by western blotting.

Results

Enhanced mitochondrial respiration coupled to ATP production was observed in SSc fibroblasts at the expense of spare respiratory capacity. Although no difference was found in glycolysis when comparing SSc with healthy control fibroblasts, levels of phophofructokinase-1 isoform PFKM were significantly lower in SSc fibroblasts (P<0.05). Our results suggest that the number of respirasomes is decreased in the SSc mitochondria; however, the organelles formed a hyperfused network, which is thought to increase mitochondrial ATP production through complementation. The increased mitochondrial fusion correlated with a change in expression levels of regulators of mitochondrial morphology, including decreased levels of DRP1, increased levels of MIEF2 and changes in OPA1 isoform ratios. TGF-β1 treatment strongly stimulated glycolysis and mitochondrial respiration and induced the expression of fibrotic markers. The pan-PIM kinase inhibitor had no effect, whereas both ALK5 and ATM kinase inhibition abrogated TGF-β1-mediated fibroblast activation, and upregulation of glycolysis and respiration.

Conclusions

Our data provide evidence for a novel mechanism(s) by which SSc fibroblasts exhibit altered metabolic programs and highlight changes in respiration and dysregulated mitochondrial morphology and function, which can be selectively targeted by small molecule kinase inhibitors.

Combined – whole blood and skin fibroblasts- transcriptomic analysis in Psoriatic Arthritis reveals molecular signatures of activity, resistance and early response to treatment

Background

An interplay between immune cells and resident skin and joint stromal cells is implicated in psoriatic arthritis (PsA), yet the mechanisms remain elusive with a paucity of molecular biomarkers for activity and response. Combined transcriptomic and immunophenotypic analysis of whole blood and skin fibroblasts could provide further insights.

Methods

Whole blood RNA-seq was performed longitudinally in 30 subjects with PsA at the beginning, one and six months after treatment, with response defined at six months. As control groups, 10 healthy individuals and 10 subjects with rheumatoid arthritis (RA) were recruited combined with public datasets from patients with psoriasis (PsO) and systemic lupus erythematous (SLE). Differential expression analysis and weighted gene co-expression network analysis were performed to identify gene expression signatures, while deconvolution and flow cytometry to characterize the peripheral blood immune cell profile. In a subset of affected and healthy individuals, RNA-seq of skin fibroblasts was performed and subjected to CellChat analysis to identify the blood-skin fibroblast interaction network.

Results

PsA demonstrated a distinct “activity” gene signature in the peripheral blood dominated by TNF- and IFN-driven inflammation, deregulated cholesterol and fatty acid metabolism and expansion of pro-inflammatory non-classical monocytes. Comparison with the blood transcriptome of RA, PsO, and SLE revealed a “PsA-specific signature” enriched in extracellular matrix remodeling. This was further supported by the skin fibroblast gene expression profile, displaying an activated, proliferating phenotype, and by skin-blood interactome analysis revealing interactions with circulating immune cells through WNT, PDGF and immune-related semaphorins. Of note, resistance to treatment was associated with upregulation of genes involved in TGFβ signaling and angiogenesis and persistent increase of non-classical monocytes. Differentially expressed genes related to platelet activation and hippo signaling discriminated responders and non-responders as early as one month after treatment initiation.

Conclusion

Transcriptome analysis of peripheral blood and skin fibroblasts in PsA reveals a distinct disease activity signature and supports the involvement of skin fibroblasts through their activation and interaction with circulating immune cells. Aberrant TGFβ signaling and persistently increased non-classical monocytes characterize treatment-resistant PsA, with pro-inflammatory pathways related to platelet activation and Hippo signaling predicting early response to treatment.

Gelatin-lecithin-F127 gel mediated self-assembly of curcumin vesicles for enhanced wound healing

Curcumin, a principal component of Curcuma longa, has a long history of being used topically for wound healing. However, poor aqueous solubility of curcumin leads to poor topical absorption. Recently, gelatin based gel has been reported to overcome this issue. However, the release of curcumin from gelatin gel in the bioavailable or easily absorbable form is still a challenge. The present study reports the development of a composite gel prepared from gelatin, F127 and lecithin using temperature dependant gelation and loading of curcumin within it. Notably, the composite gel facilitated the release of curcumin entrapped within vesicles of ~400 nm size. Further, the composite gel exhibited increase in the storage modulus or gel strength, stability, pore size and hydrophobicity as compared to only gelatin gel. Finally, wound healing assay in murine model indicated that curcumin delivered through composite gel showed a significantly faster healing as compared to that delivered through organic solvent. This was also validated by histopathological and biochemical analysis showing better epithelization and collagen synthesis in the group dressed with curcumin containing composite gel. In conclusion, composite gel facilitated the release of bioavailable or easily absorbable curcumin which in turn enhanced the wound healing.

Fucoxanthin Attenuates the Reprogramming of Energy Metabolism during the Activation of Hepatic Stellate Cells

Hepatic stellate cells (HSC) play a major role in developing liver fibrosis. Upon activation during liver injury, activated HSC (aHSC) increase cell proliferation, fibrogenesis, contractility, chemotaxis, and cytokine release. We previously showed that aHSC have increased mitochondrial respiration but decreased glycolysis compared to quiescent HSC (qHSC). We also demonstrated that fucoxanthin (FCX), a xanthophyll carotenoid, has an anti-fibrogenic effect in HSC. The objective of this study was to investigate whether FCX attenuates metabolic reprogramming occurring during HSC activation. Mouse primary HSC were activated in the presence or absence of FCX for seven days. aHSC displayed significantly decreased glycolysis and increased mitochondrial respiration compared to qHSC, which was ameliorated by FCX present during activation. In addition, FCX partially attenuated the changes in the expression of genes involved in glycolysis and mitochondrial respiration, including hexokinase 1 (Hk1), Hk2, peroxisome proliferator-activated receptor γ coactivator 1β, and pyruvate dehydrogenase kinase 3. Our data suggest that FCX may prevent HSC activation by modulating the expression of genes crucial for metabolic reprogramming in HSC.

Pleiotropic Effects of Simvastatin and Losartan in Preclinical Models of Post-Traumatic Elbow Contracture

Elbow trauma can lead to post-traumatic joint contracture (PTJC), which is characterized by loss of motion associated with capsule/ligament fibrosis and cartilage damage. Unfortunately, current therapies are often unsuccessful or cause complications. This study aimed to determine the effects of prophylactically administered simvastatin (SV) and losartan (LS) in two preclinical models of elbow PTJC: an in vivo elbow-specific rat injury model and an in vitro collagen gel contraction assay. The in vivo elbow rat (n = 3-10/group) injury model evaluated the effects of orally administered SV and LS at two dosing strategies [i.e., low dose/high frequency/short duration (D1) vs. high dose/low frequency/long duration (D2)] on post-mortem elbow range of motion (via biomechanical testing) as well as capsule fibrosis and cartilage damage (via histopathology). The in vitro gel contraction assay coupled with live/dead staining (n = 3-19/group) evaluated the effects of SV and LS at various concentrations (i.e., 1, 10, 100 µM) and durations (i.e., continuous, short, or delayed) on the contractibility and viability of fibroblasts/myofibroblasts [i.e., NIH3T3 fibroblasts with endogenous transforming growth factor-beta 1 (TGFβ1)]. In vivo, no drug strategy prevented elbow contracture biomechanically. Histologically, only SV-D2 modestly reduced capsule fibrosis but maintained elevated cellularity and tissue hypertrophy, and both SV strategies lessened cartilage damage. SV modest benefits were localized to the anterior region, not the posterior, of the joint. Neither LS strategy had meaningful benefits in capsule nor cartilage. In vitro, irrespective of the presence of TGFβ1, SV (≥10 μM) prevented gel contraction partly by decreasing cell viability (100 μM). In contrast, LS did not prevent gel contraction or affect cell viability. This study demonstrates that SV, but not LS, might be suitable prophylactic drug therapy in two preclinical models of elbow PTJC. Results provide initial insight to guide future preclinical studies aimed at preventing or mitigating elbow PTJC.

CXCL4 drives fibrosis by promoting several key cellular and molecular processes

Fibrosis is a major cause of mortality worldwide, characterized by myofibroblast activation and excessive extracellular matrix deposition. Systemic sclerosis is a prototypic fibrotic disease in which CXCL4 is increased and strongly correlates with skin and lung fibrosis. Here we aim to elucidate the role of CXCL4 in fibrosis development. CXCL4 levels are increased in multiple inflammatory and fibrotic mouse models, and, using CXCL4-deficient mice, we demonstrate the essential role of CXCL4 in promoting fibrotic events in the skin, lungs, and heart. Overexpressing human CXCL4 in mice aggravates, whereas blocking CXCL4 reduces, bleomycin-induced fibrosis. Single-cell ligand-receptor analysis predicts CXCL4 to affect endothelial cells and fibroblasts. In vitro, we confirm that CXCL4 directly induces myofibroblast differentiation and collagen synthesis in different precursor cells, including endothelial cells, by stimulating endothelial-to-mesenchymal transition. Our findings identify a pivotal role of CXCL4 in fibrosis, further substantiating the potential role of neutralizing CXCL4 as a therapeutic strategy.

Uncovering the molecular identity of cardiosphere-derived cells (CDCs) by single-cell RNA sequencing

Cardiosphere-derived cells (CDCs) generated from human cardiac biopsies have been shown to have disease-modifying bioactivity in clinical trials. Paradoxically, CDCs' cellular origin in the heart remains elusive. We studied the molecular identity of CDCs using single-cell RNA sequencing (sc-RNAseq) in comparison to cardiac non-myocyte and non-hematopoietic cells (cardiac fibroblasts/CFs, smooth muscle cells/SMCs and endothelial cells/ECs). We identified CDCs as a distinct and mitochondria-rich cell type that shared biological similarities with non-myocyte cells but not with cardiac progenitor cells derived from human-induced pluripotent stem cells. CXCL6 emerged as a new specific marker for CDCs. By analysis of sc-RNAseq data from human right atrial biopsies in comparison with CDCs we uncovered transcriptomic similarities between CDCs and CFs. By direct comparison of infant and adult CDC sc-RNAseq data, infant CDCs revealed GO-terms associated with cardiac development. To analyze the beneficial effects of CDCs (pro-angiogenic, anti-fibrotic, anti-apoptotic), we performed functional in vitro assays with CDC-derived extracellular vesicles (EVs). CDC EVs augmented in vitro angiogenesis and did not stimulate scarring. They also reduced the expression of pro-apoptotic Bax in NRCMs. In conclusion, CDCs were disclosed as mitochondria-rich cells with unique properties but also with similarities to right atrial CFs. CDCs displayed highly proliferative, secretory and immunomodulatory properties, characteristics that can also be found in activated or inflammatory cell types. By special culture conditions, CDCs earn some bioactivities, including angiogenic potential, which might modify disease in certain disorders.

Aligned and Oriented Collagen Nanocomposite Fibers as Substrates to Activate Fibroblasts

Purified collagen possesses weak mechanical properties, hindering its broad application in tissue engineering. Strategies based on manipulating the hydrogel to induce fiber formation or incorporate nanomaterials have been proposed to overcome this issue. Herein, we use a microfluidic device to fabricate, for the first time, collagen hydrogels with aligned and oriented fibers doped with gold nanoparticles and carbon nanotubes. Results based on rheology, atomic force microscopy, and scanning electron microscopy reveal the formation of aligned and oriented collagen fibers possessing greater rigidity and stiffness on the doped hydrogels in comparison with native collagen. The mechanical properties of the hydrogels increased with the nanomaterial loading percentage and the stiffest formulations were those prepared in the presence of carbon nanotubes. We further evaluate the in vitro response of NIH-3T3 fibroblasts to the change in stiffness. The cells were found to be viable on all substrates with directional cell growth observed for the carbon nanotube-doped collagen fibers. No significant differences in the cell area, aspect ratio, and intensification of focal adhesions driven by the increase in stiffness were noted. Nonetheless, fibroblast proliferation and secretion of TGF-β1 were greater on the hydrogels doped with carbon nanotubes. This nanomaterial-collagen composite provides unique features for cell and tissue substrate applications.

Mitochondrial Telomerase Reverse Transcriptase Protects from Myocardial Ischemia/reperfusion Injury by Improving Complex I Composition and Function

Background: The catalytic subunit of telomerase, Telomerase Reverse Transcriptase (TERT) has protective functions in the cardiovascular system. TERT is not only present in the nucleus, but also in mitochondria. However, it is unclear whether nuclear or mitochondrial TERT is responsible for the observed protection and appropriate tools are missing to dissect this. Methods: We generated new mouse models containing TERT exclusively in the mitochondria (mitoTERT mice) or the nucleus (nucTERT mice) to finally distinguish between the functions of nuclear and mitochondrial TERT. Outcome after ischemia/reperfusion, mitochondrial respiration in the heart as well as cellular functions of cardiomyocytes, fibroblasts, and endothelial cells were determined. Results: All mice were phenotypically normal. While respiration was reduced in cardiac mitochondria from TERT-deficient and nucTERT mice, it was increased in mitoTERT animals. The latter also had smaller infarcts than wildtype mice, whereas nucTERT animals had larger infarcts. The decrease in ejection fraction after one, two and four weeks of reperfusion was attenuated in mitoTERT mice. Scar size was also reduced and vascularization increased. Mitochondrial TERT protected a cardiomyocyte cell line from apoptosis. Myofibroblast differentiation, which depends on complex I activity, was abrogated in TERT-deficient and nucTERT cardiac fibroblasts and completely restored in mitoTERT cells. In endothelial cells, mitochondrial TERT enhanced migratory capacity and activation of endothelial NO synthase. Mechanistically, mitochondrial TERT improved the ratio between complex I matrix arm and membrane subunits explaining the enhanced complex I activity. In human right atrial appendages, TERT was localized in mitochondria and there increased by remote ischemic preconditioning. The Telomerase activator, TA-65 evoked a similar effect in endothelial cells, thereby increasing their migratory capacity, and enhanced myofibroblast differentiation. Conclusions: Mitochondrial, but not nuclear TERT, is critical for mitochondrial respiration and during ischemia/reperfusion injury. Mitochondrial TERT improves complex I subunit composition. TERT is present in human heart mitochondria, and remote ischemic preconditioning increases its level in those organelles. TA-65 has comparable effects ex vivo and improves migratory capacity of endothelial cells and myofibroblast differentiation. We conclude that mitochondrial TERT is responsible for cardioprotection and its increase could serve as a therapeutic strategy.

Changes in Nuclear Gene Expression Related to Mitochondrial Function Affect Extracellular Matrix, Collagens, and Focal Adhesion in Keratoconus

Purpose

Mitochondrial DNA (mtDNA) abnormalities were previously found to be causative in the pathogenesis of various diseases. Here, comprehensive mitochondrial and nuclear sequence and transcript analyses, along with analyses of the methylation aspects of nuclear genes related to mitochondrial function, were performed in patients with keratoconus (KTCN) to evaluate their contribution to the KTCN pathogenesis.

Methods

Blood mtDNA of 42 KTCN and 51 non-KTCN individuals was Sanger sequenced and analyzed along with the previously obtained corneal RNA-sequencing data of 20 KTCN and 21 non-KTCN individuals. In addition, the expression and methylation of mtDNA genes and 1223 mitochondria-related nuclear genes were evaluated.

Results

The mtDNA sequence alterations detected in blood coincided with variants identified in transcripts of the matched corneal tissues. In KTCN corneas, 97 mitochondria-related genes were deregulated, including TGFB1, P4HB, and BCL2, which are involved in the extracellular matrix (ECM) organization, collagen formation, and focal adhesion pathways. No changes in the expression of mtDNA transcripts and no differentially methylated genes among the assessed mitochondrial–nuclear gene sets were found.

Conclusions

The absence of corneal-specific mtDNA variants indicates that there is no direct relationship between mitochondrial sequence variability and KTCN phenotype in the studied individuals. However, the identified KTCN-specific transcriptomic alterations of the nuclear genes directly related to the mitochondria functioning point to their possible involvement in the ECM organization, collagen formation, and focal adhesion.

Translational Relevance

The identification of abnormalities within nuclear genes regulating ECM formation, collagen synthesis, and/or focal adhesion may form the basis of future treatment strategies or predict the progression of corneal changes in KTCN.

Myofibroblast fate plasticity in tissue repair and fibrosis: Deactivation, apoptosis, senescence and reprogramming

In response to tissue injury, fibroblasts differentiate into professional repair cells called myofibroblasts, which orchestrate many aspects of the normal tissue repair programme including synthesis, deposition and contraction of extracellular matrix proteins, leading to wound closure. Successful tissue repair responses involve termination of myofibroblast activities in order to prevent pathologic fibrotic scarring. Here, we discuss the cellular and molecular mechanisms limiting myofibroblast activities during physiological tissue repair, including myofibroblast deactivation, apoptosis, reprogramming and immune clearance of senescent myofibroblasts. In addition, we summarize pathological mechanisms leading to myofibroblast persistence and survival, a hallmark of fibrotic diseases. Finally, we discuss emerging anti-fibrotic therapies aimed at targeting myofibroblast fate such as senolytics, gene therapy, cellular immunotherapy and CAR-T cells.

TGF Beta Induces Vitamin D Receptor and Modulates Mitochondrial Activity of Human Pancreatic Cancer Cells

The inflammatory cytokine TGFβ is both a tumor suppressor during cancer initiation and a promoter of metastasis along cancer progression. Inflammation and cancer are strictly linked, and cancer onset often correlates with the insufficiency of vitamin D, known for its anti-inflammatory properties. In this study, we investigated the interplay between TGFβ and vitamin D in two models of human pancreatic cancer, and we analyzed the metabolic effects of a prolonged TGFβ treatment mimicking the inflammatory environment of pancreatic cancer in vivo. We confirmed the induction of the vitamin D receptor previously described in epithelial cells, but the inhibitory effects of vitamin D on epithelial-mesenchymal transition (EMT) were lost when the hormone was given after a long treatment with TGFβ. Moreover, we detected an ROS-mediated toxicity of the acute treatment with TGFβ, whereas a chronic exposure to low doses had a protumorigenic effect. In fact, it boosted the mitochondrial respiration and cancer cell migration without ROS production and cytotoxicity. Our observations shed some light on the multifaceted role of TGFβ in tumor progression, revealing that a sustained exposure to TGFβ at low doses results in an irreversibly increased EMT associated with a metabolic modulation which favors the formation of metastasis.

Nanoparticle conjugation of ginsenoside Rb3 inhibits myocardial fibrosis by regulating PPARα pathway

BACKGROUND

Cardiac fibrosis occurs in ischemic and non-ischemic heart failure, hereditary cardiomyopathy, diabetes and aging. Energy metabolism, which serves a crucial function in the course and treatment of cardiovascular diseases, might have therapeutic benefits for myocardial fibrosis. Ginsenoside Rb3 (G-Rb3) is one of the main components of Ginseng and exhibits poor oral bioavailability but still exerts regulate energy metabolism effects in some diseases. Therefore, the study investigated the effect of chitosan (CS) @ sodium tripolyphosphate (TPP) nanoparticles conjugation with ginsenoside Rb3 (NpRb3) on myocardial fibrosis and studied its possible mechanisms. The results showed that NpRb3 directly participates in the remodeling of myocardial energy metabolism and the regulation of perixisome proliferation-activated receptor alpha (PPARα), thereby improving the degree of myocardial fibrosis. The study also verifies the protective effect of NpRb3 on energy metabolism and mitochondrial function by targeting the PPARα pathway. Therefore, the prepared nanodrug carrier may be a potential solution for the delivery of G-Rb3, which is a promising platform for oral treatment of myocardial fibrosis.

A Metabolic Reprogramming of Glycolysis and Glutamine Metabolism Is a Requisite for Renal Fibrogenesis-Why and How?

Chronic Kidney Disease (CKD) is characterized by organ remodeling and fibrosis due to failed wound repair after on-going or severe injury. Key to this process is the continued activation and presence of matrix-producing renal fibroblasts. In cancer, metabolic alterations help cells to acquire and maintain a malignant phenotype. More recent evidence suggests that something similar occurs in the fibroblast during activation. To support these functions, pro-fibrotic signals released in response to injury induce metabolic reprograming to meet the high bioenergetic and biosynthetic demands of the (myo)fibroblastic phenotype. Fibrogenic signals such as TGF-β1 trigger a rewiring of cellular metabolism with a shift toward glycolysis, uncoupling from mitochondrial oxidative phosphorylation, and enhanced glutamine metabolism. These adaptations may also have more widespread implications with redirection of acetyl-CoA directly linking changes in cellular metabolism and regulatory protein acetylation. Evidence also suggests that injury primes cells to these metabolic responses. In this review we discuss the key metabolic events that have led to a reappraisal of the regulation of fibroblast differentiation and function in CKD.

AITC inhibits fibroblast-myofibroblast transition via TRPA1-independent MAPK and NRF2/HO-1 pathways and reverses corticosteroids insensitivity in human lung fibroblasts

Background

Little is known on the role of transient receptor potential ankyrin 1 (TRPA1) in fibroblast—myofibroblast transition (FMT) that can lead to airway remodeling which is a major problem for severe asthma and fibrosis. Thus, this study investigated the effect of TRPA1 modulators on transforming growth factor beta 1(TGF-β1) -treated lung fibroblasts.

Methods

MRC-5 cells were preincubated with TGF-β1 for 24 h. TRPA1 agonist or antagonist were added and further incubated for 24 h. The changes in TRPA1 and alpha-smooth muscle actin (α-SMA) expressions by stimuli were evaluated using qRT-PCR, western blot and immunohistochemical analyses. Statistical significance was determined by using one- or two-way ANOVA, followed by Bonferroni’s post hoc analysis for comparison of multiple groups and paired 2-tailed Student’s t-test between 2 groups.

Results

MRC-5 cells treated by TGF-β1 significantly upregulated α-SMA mRNA expressions (P < 0.01), but downregulated TRPA1 gene expression (P < 0.001). Post-treatment of TRPA1 activator, allyl isothiocyanate (AITC), after TGF-β1 significantly downregulated the α-SMA gene induction (P < 0.01 at 24 h), protein expression (P < 0.05) and immunoreactivity with stress fibers (P < 0.05). On the other hand, TRPA1 antagonist HC-030031 did not prevent this effect, and instead tended to facilitate the suppressive effect of AITC when co-stimulated. AITC significantly increased phosphorylated- extracellular signal-regulated kinase (ERK) 1/2 and heme oxygenase (HO)-1 protein expressions (P < 0.05) in TGF-β1-treated cells. Combined inhibition with ERK1/2 mitogen-activated protein kinase (MAPK) and nuclear factor erythroid 2-related factor (NRF2) almost completely reversed AITC-induced α-SMA suppression (P < 0.05). Dexamethasone was not able to inhibit the upregulated α-SMA induction by TGF-β1. However, AITC improved dexamethasone-insensitive myodifferentiation in the presence of the corticosteroid (P < 0.01).

Conclusion

We found that AITC exerts protective effect on TGF-β1-induced α-SMA induction by activating ERK1/2 MAPK and NRF2/HO-1 pathways in lung fibroblasts. It also overcomes corticosteroids insensitivity in TGF-β1-induced α-SMA induction. TRPA1 antagonist modulates the suppressive effect, but not prevent it. AITC and TRPA1 antagonist may be therapeutic agents in treating chronic respiratory diseases.

A proline rich protein from the gingival seal around teeth exhibits antimicrobial properties against Porphyromonas gingivalis

The gingival seal around teeth prevents bacteria from destroying the tooth-supporting tissues and disseminating throughout the body. Porphyromonas gingivalis, a major periodontopathogen, degrades components of the specialized extracellular matrix that mediates attachment of the gingiva to the tooth. Of these, secretory calcium-binding phosphoprotein proline-glutamine rich 1 (SCPPPQ1) protein has a distinctive resistance to degradation, suggesting that it may offer resistance to bacterial attack. In silico analysis of its amino acid sequence was used to explore its molecular characteristics and to predict its two- and three-dimensional structure. SCPPPQ1 exhibits similarities with both proline-rich and cationic antimicrobial proteins, suggesting a putative antimicrobial potential. A combination of imaging approaches showed that incubation with 20 μM of purified SCPPPQ1 decrease bacterial number (p < 0.01). Fluorescence intensity decreased by 70% following a 2 h incubation of Porphyromonas gingivalis with the protein. Electron microscopy analyses revealed that SCPPPQ1 induced bacterial membrane disruption and breaches. While SCPPPQ1 has no effect on mammalian cells, our results suggest that it is bactericidal to Porphyromonas gingivalis, and that this protein, normally present in the gingival seal, may be exploited to maintain a healthy seal and prevent systemic dissemination of bacteria.

Upstream Regulator Analysis of Wooden Breast Myopathy Proteomics in Commercial Broilers and Comparison to Feed Efficiency Proteomics in Pedigree Male Broilers

In an effort to understand the apparent trade-off between the continual push for growth performance and the recent emergence of muscle pathologies, shotgun proteomics was conducted on breast muscle obtained at ~8 weeks from commercial broilers with wooden breast (WB) myopathy and compared with that in pedigree male (PedM) broilers exhibiting high feed efficiency (FE). Comparison of the two proteomic datasets was facilitated using the overlay function of Ingenuity Pathway Analysis (IPA) (Qiagen, CA, USA). We focused on upstream regulator analysis and disease-function analysis that provides predictions of activation or inhibition of molecules based on (a) expression of downstream target molecules, (b) the IPA scientific citation database. Angiopoeitin 2 (ANGPT2) exhibited the highest predicted activation Z-score of all molecules in the WB dataset, suggesting that the proteomic landscape of WB myopathy would promote vascularization. Overlaying the FE proteomics data on the WB ANGPT2 upstream regulator network presented no commonality of protein expression and no prediction of ANGPT2 activation. Peroxisome proliferator coactivator 1 alpha (PGC1α) was predicted to be inhibited, suggesting that mitochondrial biogenesis was suppressed in WB. PGC1α was predicted to be activated in high FE pedigree male broilers. Whereas RICTOR (rapamycin independent companion of mammalian target of rapamycin) was predicted to be inhibited in both WB and FE datasets, the predictions were based on different downstream molecules. Other transcription factors predicted to be activated in WB muscle included epidermal growth factor (EGFR), X box binding protein (XBP1), transforming growth factor beta 1 (TGFB1) and nuclear factor (erythroid-derived 2)-like 2 (NFE2L2). Inhibitions of aryl hydrocarbon receptor (AHR), AHR nuclear translocator (ARNT) and estrogen related receptor gamma (ESRRG) were also predicted in the WB muscle. These findings indicate that there are considerable differences in upstream regulators based on downstream protein expression observed in WB myopathy and in high FE PedM broilers that may provide additional insight into the etiology of WB myopathy.

TGF-β1 is a regulator of the pyruvate dehydrogenase complex in fibroblasts

TGF-β1 reprograms metabolism in renal fibroblasts, inducing a switch from oxidative phosphorylation to aerobic glycolysis. However, molecular events underpinning this are unknown. Here we identify that TGF-β1 downregulates acetyl-CoA biosynthesis via regulation of the pyruvate dehydrogenase complex (PDC). Flow cytometry showed that TGF-β1 reduced the PDC subunit PDH-E1α in fibroblasts derived from injured, but not normal kidneys. An increase in expression of PDH kinase 1 (PDK1), and reduction in the phosphatase PDP1, were commensurate with net phosphorylation and inactivation of PDC. Over-expression of mutant PDH-E1α, resistant to phosphorylation, ameliorated effects of TGF-β1, while inhibition of PDC activity with CPI-613 was sufficient to induce αSMA and pro-collagen I expression, markers of myofibroblast differentiation and fibroblast activation. The effect of TGF-β1 on PDC activity, acetyl-CoA, αSMA and pro-collagen I was also ameliorated by sodium dichloroacetate, a small molecule inhibitor of PDK. A reduction in acetyl-CoA, and therefore acetylation substrate, also resulted in a generalised loss of protein acetylation with TGF-β1. In conclusion, TGF-β1 in part regulates fibroblast activation via effects on PDC activity.

Mitochondrial dysfunction in lung ageing and disease

Mitochondrial biology has seen a surge in popularity in the past 5 years, with the emergence of numerous new avenues of exciting mitochondria-related research including immunometabolism, mitochondrial transplantation and mitochondria-microbe biology. Since the early 1960s mitochondrial dysfunction has been observed in cells of the lung in individuals and in experimental models of chronic and acute respiratory diseases. However, it is only in the past decade with the emergence of more sophisticated tools and methodologies that we are beginning to understand how this enigmatic organelle regulates cellular homeostasis and contributes to disease processes in the lung. In this review, we highlight the diverse role of mitochondria in individual lung cell populations and what happens when these essential organelles become dysfunctional with ageing and in acute and chronic lung disease. Although much remains to be uncovered, we also discuss potential targeted therapeutics for mitochondrial dysfunction in the ageing and diseased lung.

Myofibroblasts and Fibrosis: Mitochondrial and Metabolic Control of Cellular Differentiation

Cardiac fibrosis is mediated by the activation of resident cardiac fibroblasts, which differentiate into myofibroblasts in response to injury or stress. Although myofibroblast formation is a physiological response to acute injury, such as myocardial infarction, myofibroblast persistence, as occurs in heart failure, contributes to maladaptive remodeling and progressive functional decline. Although traditional pathways of activation, such as TGFβ (transforming growth factor β) and AngII (angiotensin II), have been well characterized, less understood are the alterations in mitochondrial function and cellular metabolism that are necessary to initiate and sustain myofibroblast formation and function. In this review, we highlight recent reports detailing the mitochondrial and metabolic mechanisms that contribute to myofibroblast differentiation, persistence, and function with the hope of identifying novel therapeutic targets to treat, and potentially reverse, tissue organ fibrosis.

Type I Collagen Suspension Induces Neocollagenesis and Myodifferentiation in Fibroblasts In Vitro

The ability of a collagen-based matrix to support cell proliferation, migration, and infiltration has been reported; however, the direct effect of an aqueous collagen suspension on cell cultures has not been studied yet. In this work, the effects of a high-concentration aqueous suspension of a micronized type I equine collagen (EC-I) have been evaluated on a normal mouse fibroblast cell line. Immunofluorescence analysis showed the ability of EC-I to induce a significant increase of type I and III collagen levels, parallel with overexpression of crucial proteins in collagen biosynthesis, maturation, and secretion, prolyl 4-hydroxylase (P4H) and heat shock protein 47 (HSP47), as demonstrated by western blot experiments. The treatment led, also, to an increase of α-smooth muscle actin (α-SMA) expression, evaluated through western blot analysis, and cytoskeletal reorganization, as assessed by phalloidin staining. Moreover, scanning electron microscopy analysis highlighted the appearance of plasma membrane extensions and blebbing of extracellular vesicles. Altogether, these results strongly suggest that an aqueous collagen type I suspension is able to induce fibroblast myodifferentiation. Moreover, our findings also support in vitro models as a useful tool to evaluate the effects of a collagen suspension and understand the molecular signaling pathways possibly involved in the effects observed following collagen treatment in vivo.

TGFβ-dependent mitochondrial biogenesis is activated during definitive endoderm differentiation

Whether mitochondrial remodeling and metabolic reprogramming occur during the differentiation of human embryonic stem cells (hESCs) to definitive endoderm (DE) is unknown. We found that fragmented and punctate mitochondria in undifferentiated hESCs progressively fused into an extensive and branched network upon DE differentiation. Mitochondrial mass and mitochondrial DNA (mtDNA) content were significantly increased with the upregulated expression of mitochondrial biogenesis regulator PGC1-A upon DE differentiation, accompanied by the rise of the amount of ATP (2.5-fold) and its by-product reactive oxygen species (2.0-fold). We observed that in contrast to a shutoff of glycolysis, expressions of oxidative phosphorylation (OXPHOS) genes were increased, indicating that a transition from glycolysis to OXPHOS was tightly coupled to DE differentiation. In the meantime, we discovered that inhibition of TGF-β signaling led to impaired mitochondrial biogenesis and disturbed metabolic switch upon DE differentiation. Our work, for the first time, reports that TGF-β signaling-dependent mitochondrial biogenesis and metabolic reprogramming occur during early endodermal differentiation.

Mangiferin activates Nrf2 to attenuate cardiac fibrosis via redistributing glutaminolysis-derived glutamate

Cardiac injury is followed by fibrosis, characterized by myofibroblast activation. Excessive deposition of extracellular matrix (ECM) impairs the plasticity of myocardium and results in myocardial systolic and diastolic dysfunction. Mangiferin is a xanthonoid derivative rich in plants mangoes and iris unguicularis, exhibiting the ability to ameliorate metabolic disorders. This study aims to investigate whether mangiferin attenuates cardiac fibrosis via redox regulation. The transverse aortic constriction (TAC) in mice induced cardiac fibrosis with impaired heart function. Oral administration of mangiferin (50 mg/kg, 4 weeks) inhibited myofibroblast activation with reduced formation of ECM. The impaired left ventricular contractive function was also improved by mangiferin. TGF-β1 stimulation increased glutaminolysis to fuel intracellular glutamate pool for the increased demands of nutrients to support cardiac myofibroblast activation. Mangiferin degraded Keap1 to promote Nrf2 protein accumulation by improving its stability, leading to Nrf2 activation. Nrf2 transcriptionally promotes the synthesis of antioxidant proteins. By activating Nrf2, mangiferin promoted the synthesis of glutathione (GSH) in cardiac fibroblasts, likely due to the consumption of glutaminolysis-derived glutamate as a source. Meanwhile, mangiferin promoted the exchange of intracellular glutamate for the import of extracellular cystine to support GSH generation. As a result of redistribution, the reduced glutamate availability failed to support myofibroblast activation. In support of this, the addition of extracellular glutamate or α-ketoglutarate diminished the inhibitory effects of mangiferin on cardiac myofibroblast proliferation and activation. Moreover, cardiac knockdown of Nrf2 attenuated the cardioprotective effects of mangiferin in mice subjected to TAC. In conclusion, we demonstrated that activated myofibroblasts were sensitive to glutamate availability. Mangiferin activated Nrf2 and redistributed intracellular glutamate for the synthesis of GSH, consequently impairing cardiac myofibroblast activation due to decreased glutamate availability. These results address that pharmacological activation of Nrf2 could restrain cardiac fibrosis via metabolic regulation.

New Insights into the Implication of Mitochondrial Dysfunction in Tissue, Peripheral Blood Mononuclear Cells, and Platelets during Lung Diseases

Lung diseases such as chronic obstructive pulmonary disease, asthma, pulmonary arterial hypertension, or idiopathic pulmonary fibrosis are major causes of morbidity and mortality. Complex, their physiopathology is multifactorial and includes lung mitochondrial dysfunction and enhanced reactive oxygen species (ROS) release, which deserves increased attention. Further, and importantly, circulating blood cells (peripheral blood mononuclear cells-(PBMCs) and platelets) likely participate in these systemic diseases. This review presents the data published so far and shows that circulating blood cells mitochondrial oxidative capacity are likely to be reduced in chronic obstructive pulmonary disease (COPD), but enhanced in asthma and pulmonary arterial hypertension in a context of increased oxidative stress. Besides such PBMCs or platelets bioenergetics modifications, mitochondrial DNA (mtDNA) changes have also been observed in patients. These new insights open exciting challenges to determine their role as biomarkers or potential guide to a new therapeutic approach in lung diseases.

Exogenous dihydrosphingosine 1 phosphate mediates collagen synthesis in cardiac fibroblasts through JAK/STAT signalling and regulation of TIMP1

Cardiac fibrosis and myocyte hypertrophy are hallmarks of the cardiac remodelling process in cardiomyopathies such as heart failure (HF). Dyslipidemia or dysregulation of lipids contribute to HF. The dysregulation of high density lipoproteins (HDL) could lead to altered levels of other lipid metabolites that are bound to it such as sphingosine-1- phosphate (S1P). Recently, it has been shown that S1P and its analogue dihydrosphingosine-1-phosphate (dhS1P) are bound to HDL in plasma. The effects of dhS1P on cardiac cells have been obscure. In this study, we show that extracellular dhS1P is able to increase collagen synthesis in neonatal rat cardiac fibroblasts (NCFs) and cause hypertrophy of neonatal cardiac myocytes (NCMs). The janus kinase/signal transducer and activator (JAK/STAT) signalling pathway was involved in the increased collagen synthesis by dhS1P, through sustained increase of tissue inhibitor of matrix metalloproteinase 1 (TIMP1). Extracellular dhS1P increased phosphorylation levels of STAT1 and STAT3 proteins, also caused an early increase in gene expression of transforming growth factor-β (TGFβ), and sustained increase in TIMP1. Inhibition of JAKs led to inhibition of TIMP1 and TGFβ gene and protein expression. We also show that dhS1P is able to cause NCM hypertrophy through S1P-receptor-1 (S1PR1) signalling which is opposite to that of its analogue, S1P. Taken together, our results show that dhS1P increases collagen synthesis in cardiac fibroblasts causing fibrosis through dhS1P-JAK/STAT-TIMP1 signalling.

Modulation of Foreign Body Reaction against PDMS Implant by Grafting Topographically Different Poly(acrylic acid) Micropatterns

The surface of poly(dimethylsiloxane) (PDMS) is grafted with poly(acrylic acid) (PAA) layers via surface-initiated photopolymerization to suppress the capsular contracture resulting from a foreign body reaction. Owing to the nature of photo-induced polymerization, various PAA micropatterns can be fabricated using photolithography. Hole and stripe micropatterns ≈100-µm wide and 3-µm thick are grafted onto the PDMS surface without delamination. The incorporation of PAA micropatterns provides not only chemical cues by hydrophilic PAA microdomains but also topographical cues by hole or stripe micropatterns. In vitro studies reveal that a PAA-grafted PDMS surface has a lower proliferation of both macrophages (Raw 264.7) and fibroblasts (NIH 3T3) regardless of the pattern presence. However, PDMS with PAA micropatterns, especially stripe micropatterns, minimizes the aggregation of fibroblasts and their subsequent differentiation into myofibroblasts. An in vivo study also shows that PDMS samples with stripe micropatterns polarized macrophages into anti-inflammatory M2 macrophages and most effectively inhibits capsular contracture, which is demonstrated by investigation of inflammation score, transforming-growth-factor-β expression, number of macrophages, and myofibroblasts as well as the collagen density and capsule thickness.

Emerging role of mitophagy in cardiovascular physiology and pathology

Healthy mitochondrial function is imperative for most tissues, but especially those with a high energy demand. Robust evidence linking mitochondrial dysfunction with cardiovascular disease has demonstrated that mitochondrial activity is highly relevant to cardiac muscle performance. Mitochondrial homeostasis is maintained through coordination among the processes that comprise the so-called mitochondrial dynamics machinery. The most-studied elements of cardiac mitochondrial dynamics are mitochondrial fission and fusion, biogenesis and degradation. Selective autophagic removal of mitochondria (mitophagy) is essential for clearing away defective mitochondria but can lead to cell damage and death if not tightly controlled. In cardiovascular cells such as cardiomyocytes and cardiac fibroblasts, mitophagy is involved in metabolic activity, cell differentiation, apoptosis and other physiological processes related to major phenotypic changes. Modulation of mitophagy has detrimental and/or beneficial outcomes in various cardiovascular diseases, suggesting that a deeper understanding of the mechanisms underlying mitochondrial degradation in the heart could provide valuable clinical insights. Here, we discuss current evidence supporting the role of mitophagy in cardiac pathophysiology, with an emphasis on different research models and their interpretations; basic concepts related to this selective autophagy; and the most commonly used experimental approaches for studying this mechanism. Finally, we provide a comprehensive literature analysis on the role of mitophagy in heart failure, ischemia/reperfusion, diabetic cardiomyopathy and other cardiovascular diseases, as well as its potential biomedical applications.

Impact of statins on cellular respiration and de-differentiation of myofibroblasts in human failing hearts

AIMS

Fibroblast to myofibroblast trans-differentiation with altered bioenergetics precedes cardiac fibrosis (CF). Either prevention of differentiation or promotion of de-differentiation could mitigate CF-related pathologies. We determined whether 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitors-statins, commonly prescribed to patients at risk of heart failure (HF)-can de-differentiate myofibroblasts, alter cellular bioenergetics, and impact the human ventricular fibroblasts (hVFs) in HF patients.

METHODS AND RESULTS

Either in vitro statin treatment of differentiated myofibroblasts (n = 3-6) or hVFs, isolated from human HF patients under statin therapy (HF + statin) vs. without statins (HF) were randomly used (n = 4-12). In vitro, hVFs were differentiated by transforming growth factor-β1 (TGF-β1) for 72 h (TGF-72 h). Differentiation status and cellular oxygen consumption rate (OCR) were determined by α-smooth muscle actin (α-SMA) expression and Seahorse assay, respectively. Data are mean ± SEM except Seahorse (mean ± SD); P < 0.05, considered significant. In vitro, statins concentration-dependently de-differentiated the myofibroblasts. The respective half-maximal effective concentrations were 729 ± 13 nmol/L (atorvastatin), 3.6 ± 1 μmol/L (rosuvastatin), and 185 ± 13 nmol/L (simvastatin). Mevalonic acid (300 μmol/L), the reduced product of HMG-CoA, prevented the statin-induced de-differentiation (α-SMA expression: 31.4 ± 10% vs. 58.6 ± 12%). Geranylgeranyl pyrophosphate (GGPP, 20 μmol/L), a cholesterol synthesis-independent HMG-CoA reductase pathway intermediate, completely prevented the statin-induced de-differentiation (α-SMA/GAPDH ratios: 0.89 ± 0.05 [TGF-72 h + 72 h], 0.63 ± 0.02 [TGF-72 h + simvastatin], and 1.2 ± 0.08 [TGF-72 h + simvastatin + GGPP]). Cellular metabolism involvement was observed when co-incubation of simvastatin (200 nmol/L) with glibenclamide (10 μmol/L), a K_ATP channel inhibitor, attenuated the simvastatin-induced de-differentiation (0.84 ± 0.05). Direct inhibition of mitochondrial respiration by oligomycin (1 ng/mL) also produced a de-differentiation effect (0.33 ± 0.02). OCR (pmol O₂ /min/μg protein) was significantly decreased in the simvastatin-treated hVFs, including basal (P = 0.002), ATP-linked (P = 0.01), proton leak-linked (P = 0.01), and maximal (P < 0.001). The OCR inhibition was prevented by GGPP (basal OCR [P = 0.02], spare capacity OCR [P = 0.008], and maximal OCR [P = 0.003]). Congruently, hVFs from HF showed an increased population of myofibroblasts while HF + statin group showed significantly reduced cellular respiration (basal OCR [P = 0.021], ATP-linked OCR [P = 0.047], maximal OCR [P = 0.02], and spare capacity OCR [P = 0.025]) and myofibroblast differentiation (α-SMA/GAPDH: 1 ± 0.19 vs. 0.23 ± 0.06, P = 0.01).

CONCLUSIONS

This study demonstrates the de-differentiating effect of statins, the underlying GGPP sensitivity, reduced OCR with potential activation of K_ATP channels, and their impact on the differentiation magnitude of hVFs in HF patients. This novel pleiotropic effect of statins may be exploited to reduce excessive CF in patients at risk of HF.

The cellular landscape by cryo soft X-ray tomography

Imaging techniques in structural cell biology are indispensable to understand cell organization and machinery. In this frame, cryo soft X-ray tomography (cryo-SXT), a synchrotron-based imaging technique, is used to analyze the ultrastructure of intact, cryo-preserved cells at nanometric spatial resolution bridging electron microscopy and visible light fluorescence. With their unique interaction with matter and high penetration depth, X-rays are a very useful and complementary source to obtain both high-resolution and quantitative information. In this review, we are elaborating a typical cryo correlative workflow at the Mistral Beamline at the Alba Synchrotron (Spain) with the goal of providing a cartographic description of the cell by cryo-SXT that illustrates the possibilities this technique brings for specific localization of cellular features, organelle organization, and particular events in specific structural cell biology research.

TGF-β1 modifies histone acetylation and acetyl-coenzyme A metabolism in renal myofibroblasts

Histone acetylation is an important modulator of gene expression in fibrosis. This study examined the effect of the pre-eminent fibrogenic cytokine TGF-b1 on histone 3 (H3) acetylation and its regulatory kinetics in renal myofibroblasts. Fibroblasts propagated from rat kidneys after ureteric obstruction were treated with recombinant TGF-b1 or vehicle for 48 hours. TGF-b1 -induced myofibroblast activation was accompanied by a net decrease in total H3 acetylation, although changes in individual marks were variable. This was paralleled by a generalised reduction in histone acetyltransferases (HAT), and divergent changes in histone deacetylase (HDAC) enzymes at both transcript and protein levels. Globally this was manifest in a reduction in total HAT activity and increase in HDAC activity. TGF-b1 induced a shift in cellular metabolism from oxidative respiration to aerobic glycolysis resulting in reduced acetyl-CoA. The reduction in total H3 acetylation could be rescued by providing exogenous citrate or alternative sources of acetyl-CoA, without ameliorating changes in HAT/HDAC activity. In conclusion, TGF-b1 produces a metabolic reprogramming in renal fibroblasts, with less H3 acetylation through reduced acetylation, increased deacetylation and changes in carbon availability. Our results suggest that acetyl-CoA availability predominates over HAT and HDAC activity as a key determinant of H3 acetylation in response to TGF-b1.

Open multi-culture platform for simple and flexible study of multi-cell type interactions

The study of multi-cell-type (MCT) interactions has the potential to significantly impact our understanding of tissue and disease biology. Such studies require innovative culture tools for unraveling the contributions of each cell type. Micro- and macro-scale platforms for MCT culture each have different advantages and disadvantages owing to their widely different capabilities, availability, and ease-of-use. However, as evidenced in the literature, there are very few examples of MCT studies and culture platforms, suggesting both biological and technical barriers. We have developed an open multi-culture platform to promote more rapid progress by integrating advantages of both micro- and macro-scale culture devices. The proposed open multi-culture platform addresses technical barriers by allowing easy customization, independent control of basic physical culture parameters, and incorporation of multiple culture modalities (e.g., 2D, 3D, transwell, and spheroid). The design also permits the user to obtain independent endpoints for each culture region. We demonstrate use of the platform in two example studies where we evaluated how cell ratio and cell types influence the response of triple negative breast cancer cells to heat damage and Hedgehog signaling. We also show that the platform can improve soluble factor transport between cell types compared to compartmentalized macro- and micro-scale alternatives. Last, we examine current and future challenges of the platform. We envision simple, yet flexible and customizable, platforms such as this will be important for advancing in vitro study of tissue and tumor biology.

Single-nucleus transcriptomic survey of cell diversity and functional maturation in postnatal mammalian hearts

A fundamental challenge in understanding cardiac biology and disease is that the remarkable heterogeneity in cell type composition and functional states have not been well characterized at single-cell resolution in maturing and diseased mammalian hearts. Massively parallel single-nucleus RNA sequencing (snRNA-seq) has emerged as a powerful tool to address these questions by interrogating the transcriptome of tens of thousands of nuclei isolated from fresh or frozen tissues. snRNA-seq overcomes the technical challenge of isolating intact single cells from complex tissues, including the maturing mammalian hearts; reduces biased recovery of easily dissociated cell types; and minimizes aberrant gene expression during the whole-cell dissociation. Here we applied sNucDrop-seq, a droplet microfluidics-based massively parallel snRNA-seq method, to investigate the transcriptional landscape of postnatal maturing mouse hearts in both healthy and disease states. By profiling the transcriptome of nearly 20,000 nuclei, we identified major and rare cardiac cell types and revealed significant heterogeneity of cardiomyocytes, fibroblasts, and endothelial cells in postnatal developing hearts. When applied to a mouse model of pediatric mitochondrial cardiomyopathy, we uncovered profound cell type-specific modifications of the cardiac transcriptional landscape at single-nucleus resolution, including changes of subtype composition, maturation states, and functional remodeling of each cell type. Furthermore, we employed sNucDrop-seq to decipher the cardiac cell type-specific gene regulatory network (GRN) of GDF15, a heart-derived hormone and clinically important diagnostic biomarker of heart disease. Together, our results present a rich resource for studying cardiac biology and provide new insights into heart disease using an approach broadly applicable to many fields of biomedicine.

Differentiated mitochondrial function in mouse 3T3 fibroblasts and human epithelial or endothelial cells in response to chemical exposure

Mouse 3T3 fibroblasts are commonly used for in vitro toxicity testing; however, their sensitivity to stimuli is not well defined. To assess the sensitivity of the 3T3 cell line, the study compared the changes in mitochondrial membrane potential (MMP) occurring after exposure to eight chemicals known to demonstrate pro-apoptotic activity (glycerol, isopropanol, ethanol, paracetamol, propranolol, cobalt chloride, formaldehyde and atropine). Five cell lines were used as follows: mouse 3T3 fibroblasts, human epithelial cells (A549, Caco-2 and HepG2) and human endothelial cells (HMEC-1). Cell sensitivity was assessed based on the total area under and over the dose-response curves (AUOC) in relation to baselines. The 3T3 fibroblasts had the highest AUOC values and were the most sensitive to the action of all the examined chemicals, with the exception of formaldehyde. Significant changes in MMP between the 3T3 cell line and other cells were observed after cell treatment with atropine (A549, Caco-2 or HMEC-1 cells vs 3T3 cells, P < 0.05), propranolol (A549 vs 3T3 cells, P < 0.01; HepG2 vs 3T3 cells, P < 0.05), cobalt chloride (A549 cells vs 3T3 cells, P < 0.01) or ethanol (HMEC-1 vs 3T3, P < 0.05). Formaldehyde appeared the most toxic compound for Caco-2 cells (Caco-2 vs 3T3 cells, P < 0.05). The surface areas (AUOC) calculated for each other chemical and obtained for HepG2, Caco-2, A549 and HMEC-1 did not differ significantly between cell lines. We postulate that mouse 3T3 fibroblasts demonstrate significantly higher relative sensitivity to many agents with toxic potential.

Simvastatin reduces TGF-β1-induced SMAD2/3-dependent human ventricular fibroblasts differentiation: Role of protein phosphatase activation

BACKGROUND

Excessive cardiac fibrosis due to maladaptive remodeling leads to progression of cardiac dysfunction and is modulated by TGF-β1-activated intracellular phospho-SMAD signaling effectors and transcription regulators. SMAD2/3 phosphorylation, regulated by protein-phosphatases, has been studied in different cell types, but its role in human ventricular fibroblasts (hVFs) is not defined as a target to reduce cytokine-mediated excessive fibrotic response and adverse cardiac remodeling. Statins are a class of drugs reported to reduce cardiac fibrosis, although underlying mechanisms are not completely understood. We aimed to assess whether simvastatin-mediated reduction in TGF-β1-augmented profibrotic response involves reduction in phospho-SMAD2/3 owing to activation of protein-phosphatase in hVFs.

METHODS AND RESULTS

Cultures of hVFs were used. Effect of simvastatin on TGF-β1-treated hVF proliferation, cytotoxicity, myofibroblast differentiation/activation, profibrotic gene expression and protein-phosphatase activity was assessed. Simvastatin (1 μM) reduced effect of TGF-β1 (5 ng/mL) on hVF proliferation, myofibroblast differentiation (reduced α-smooth muscle actin [α-SMA-expression]) and activation (decreased procollagen-peptide release). Simvastatin also reduced TGF-β1-stimulated time-dependent increases in SMAD2/3 phosphorylation and nuclear translocation, mediated through catalytic activation of protein-phosphatases PPM1A and PP2A, which physically interact with SMAD2/3, thereby promoting their dephosphorylation. Effect of simvastatin on TGF-β1-induced fibroblast activation was annulled by okadaic acid, an inhibitor of protein-phosphatase.

CONCLUSIONS

This proof-of-concept study using an in vitro experimental cell culture model identifies the protective role of simvastatin against TGF-β1-induced hVF transformation into activated myofibroblasts through activation of protein phosphatase, a novel target that can be therapeutically modulated to curb excessive cardiac fibrosis associated with maladaptive cardiac remodeling.

Transcriptional noise in intact and TGF-beta treated human kidney cells; the importance of time-series designs

The transforming growth factor (TGF)-β signaling pathway plays a key role in various cellular processes. However, insufficient knowledge about the complex and sometimes paradoxical functions of this pathway hinders its therapeutic targeting. In this study, the transcriptional profile of seven mediators and downstream elements of the TGF-β pathway were assessed in TGF-β treated and untreated human kidney derived cells for 2 weeks in a time course manner. As expected the up-regulation of ACTA2 and COL1A2 was evident in the treated cells. However, we observed remarkable fluctuations in gene expression, even in the supposedly steady states. The magnitude of noise was diverse in the examined genes. Our findings underscore the significance of time-course designs for gene expression analyses and clearly show that misleading data can be obtained in single point measurements. Furthermore, we propose specific considerations in the interpretation of time-course data in the context of noisy gene expression.